1. Field of the Invention
The present invention relates to a single-phase motor, and more particularly to a single-phase motor in which a ring-shaped magnet is mounted to a rotor in such a fashion that a parking magnet and a Hall sensor face the ring-shaped magnet.
2. Description of the Prior Art
Generally, single-phase motors include universal motors, BLDCS, or switched reluctance motors.
FIG. 1 is a circuit diagram illustrating the circuit configuration of a conventional single-phase switched reluctance motor.
As shown in FIG. 1, the conventional single-phase switched reluctance motor (SRM) includes a driving circuit 10, a stator 20 receiving electric power from the driving circuit 10, and a rotor 30 adapted to rotate by a reluctance torque generated between the stator 20 and the rotor 30 when electric power is applied to the stator 20.
In detail, the stator 20, which is arranged outside the rotor 30, includes a yoke 22 having a cylindrical structure opened at upper and lower end thereof, six poles 24 protruded from the inner surface of the yoke 22 toward the rotor 30 while being uniformly spaced apart from one another in a circumferential direction, and field coils 26 respectively wound on the protruded poles 24, and adapted to receive current from the driving circuit 10.
The rotor 30 includes a laminated core 34 having six poles 32 protruded from the outer inner surface of the core 34 while being uniformly spaced apart from one another in a circumferential direction. A rotating shaft 12 is axially mounted to the central portion of the rotor 30 so that it rotates along with the rotor 30, thereby externally transmitting the driving force of the motor.
The driving circuit 10 receives information about the position and speed of the rotor 30, and controls the intensity of current flowing through the field coils 26 based on the received information.
In the conventional single-phase switched reluctance motor having the above mentioned configuration, when current is supplied from the driving circuit 10 to the field coils 26, a reluctance torque is generated between the stator 20 and the rotor 30, thereby causing the rotor 30 to rotate in a direction exhibiting a minimum magnetic resistance.
Meanwhile, in the conventional single-phase switched reluctance motor, auxiliary coils (not shown) are wound on respective protruded poles 24 of the stator 20 in order to allow the rotating shaft 12 to always rotate in an effective rotating direction. When the current supplied from the driving circuit 10 is cut off, each protruded pole 32 of the rotor 30 is positioned within an effective torque generating region formed by an associated one of the protruded poles 24 of the stator 20, thereby allowing the rotor 30 to be initially driven in the effective rotating direction.
Accordingly, the conventional single-phase motor should use the additional device having a complex structure for its initial driving operation and subsequent operations. For this reason, the conventional single-phase motor has a low utility.
Furthermore, the conventional single-phase motor should use an optical sensor or Hall sensor (not shown) in order to acquire the information about the position and speed of the rotor required during the operation of the motor.
The present invention has been made in view of the problems involved with the Prior art, and an object of the invention is to provide a single-phase motor which can simply achieve the setting of the initial driving position of its rotor while simply implementing means for acquiring information about the position and speed of the rotor required for the operation of the motor, so that it has a high utility.
In accordance with the present invention, this object is accomplished by providing a single-phase motor comprising: a stator; a rotor adapted to rotate when electric power is applied to the stator; a ring-shaped magnet installed to rotate along with the rotor; a parking magnet for stopping the rotor within an effective torque generating region by a magnetic force effected between the ring-shaped magnet and the parking magnet upon braking the rotor, and a sensor unit for sensing a variation in the intensity of a magnetic field generated around the ring-shaped magnet during the rotation of the rotor, thereby sensing a position and speed of the rotor.